libavcodec's zmbv decoder used to do (slow) internal colourspace conversion, this was fixed in March.
The decoder may now output AV_PIX_FMT_PAL8, AV_PIX_FMT_RGB555LE, AV_PIX_FMT_RGB565LE, AV_PIX_FMT_RGB24 or AV_PIX_FMT_BGR0 depending on the input file.
This is still an issue with VLC 2.1.4. I am experiencing this problem with the x64 version in Windows 7. This can be reproduced by capturing a video from the DOSBox application. In VLC 2.1.4, video is blank but audio can be heard.
Sorry, there is only one sample, and it works fine on 2.1.5 (Windows and Linux). So either there is a new sample, then please share it, or we close this.